Highly luminescent and uniform patterned quantum dot color converters via ligand engineering

Patterned quantum dot color converters (QDCCs) convert blue light to green and red light at the pixel level, thus having potential applications in combination with micro-LED and OLED. Lithography is a promising method to fabricate the QDCCs, however, it is still a challenge to achieve highly luminescent and stable patterned QD-photoresist (PR) thick films. Herein, a strategy is developed to fabricate high-performance patterned QDCCs using the lithography process. Firstly, the QDs are modified by replacing their native hydrophobic ligands to achieve compatibility with PRs. Then, a new ligand, diphenylphosphine oxide (DPPO), is introduced to remedy surface defects of the modified QDs. Lastly, conventional lithography is adopted to fabricate QDCCs with a pattern size of 50 µm ×10 µm and a thickness of 8 µm. The passivation with DPPO is critical to the luminescent properties of the QD-PR films. The DPPO substantially increases the PLQYs of the PR-compatible QDs and the QD-PR films, achieving a supreme PLQY of 71.7% for the green QD-PR films. The present work might shed light on improving the performance of patterned QDCCs and accelerate their applications in new types of display technology.